NUTRITIONAL AND PROTECTIVE VALUES OF FISH – WITH EMPHSIS ON OMEGA-3 FATTY ACID

U radu se iznosi važnost ribe kao živežne namirnice u pogledu bjelančevina, vitamina, mikroelemenata i makroelemenata te se ona uspoređuje s visokovrijednim namirnicama toplokrvnih životinja (meso, mlijeko i jaja). Najviše literaturnih informacija odnosi se na kemijski sastav mesa, nutritivnu i biološku vrijednost. Više radova upućuje na sastav masnih kiselina u mastima najznačajnijih slatkovodnih i morskih riba. Prema sadržaju EPA (eicosapentaenska masna kiselina, 20:5(03) i DHA (docosaheksaenska masna kiselina, 22:6ω3), meso bijelog glavaša (Hypophthalmichtis molitrix) može se uspoređivati s mesom najkvalitetnijih morskih riba. U zadnjih 20 godina velik broj autora navodi protektivnu ulogu omega-3 masnih kiselina u prevenciji srčanog i moždanog udara, ateroskleroze, visokoga krvnog tlaka, psorijaze, tromboze i artritisa.This work presents the importance of fish as a life necessity in view of proteins, vitamins, micro and macro elements and in comparison with high valued necessities of warm-blooded animals (meat, milk and eggs). Most literature information is related to the chemical components of meat, nutritional and biological values. Numerous papers have shown the components of fatty acids in fats of the most important freshwater and sea fish. According the contents of FPA (eicosapentaen fatty acids, 20:5 3) and DHA (docosaheksacn fatty acids, 22:6 3) the meat of the silver carp (Hypophthalmichtis molitrix) can be compared to that of the highest quality sea fish. In the last 20 years many authors mentioned the protective role of omega-3 fatty acids in the prevention of heart attack, stroke, artherosclerosis, high blood pressure, psoriasis, thrombosis and arthritis

THE NEEDS AND IMPORTANCE OF FATTY ACIDS IN THE NUTRITION OF FISH

Prema potrebama za esencijalnim masnim kiselinama ribe se mogu svrstati u tri skupine. Za ribe iz porodice Salrrwnidae (Oncorhynhcus kisutch, O. keta, O. nerka i O. tshawytscha) esencijalna je 18 : 3 ω u količini od 1 %. Isti učinak glede prirasta i hranidbenog koeficijenta postiže se dodatkom VNMK (visokonezasićenih masnih kiselina) ω 3 reda u količini od 9,5 %. Zahtjevnija od ostalih riba za 20 : 5 ω 3 i 22 : 6 ω 3 jest kalifornijska pastrva (Oncorhynhcus mykiss) čije potrebe iznose 1 %. Za ribe iz porodice Coregonidae (Coregonus lavaretus, C. peled i C. nasus) esencijalna je 18:3 ω 3 u količini od 1 % ili kombinacija 20 : ω 3 (0,25 %) i 22 : 6 ω 3 (0,25 %). Toplovodne ribe iz porodice Anguillidae (Anguilla anguilla i A. japonicat, Cyprinidae (Cyprinus carpio), Ictaluridae (letalurus punctatus) imaju potrebe za 18 : 2 ω 6 i 18 : 3 ω 3 u količini od 1 - 2 % ili VNMK 0,5 - 1 %. Masne kiseline ω 6 reda (18 : 2 ω 6 ili 20 : 4 ω 6) bitne su za ribe iz porodice Cichlidae (Tilapia zillii i Orechromis nilaticus) u iznosu od 1 %. Morske ribe Rhombus maximus i Pagnus major postižu najbolji prirast kada s hranom dobiavju VNMK ω 3 reda do 2 %. Ranketljive masti, eruka-kiselina iz repičinog ulja, gosipol i ciklopropenoidna kiselina iz ulja sjemenki pamuka dodani u riblju hranu uzrokuju zaostajanje u porastu i patološke promjene na jetri, bubrezima, srcu i škrgama riba.According to the needs for the essential fatty acids, the fish can be classified in three groups: For the fish from Salrrwnidae family (Oncorhynhcus kisutch, O. keta, O. nerka and O. tshawytscha) the essential is 18: 3 in the quantity of 1%. The same effect in regard to growth and nutrition coefficient can be achieved with the addition of highly unsaturated fatty acids (HUF A) ω 3 rows in the quantity of 9. 5%. The Californian trout (Oncorhynhcus mykiss) is needier than the other fish for 20: 5 ω 3 and 22: 6 ω 3. Its needs is 1%. For the fish from Coregonidae family (Coregonus lavaretus, C. peled and C. nasus) the essential is 18: 3 ω 3 in the quantity of 1% or the combination 20: 5 ω 3 (o. 25%) and 22: 6 ω 3 (O. 25%). Fresh-water fish from the Anguillidae family (Anguilla anguilla and A. japonicai, Cyprinidae family (Cyprinus carpio), Ictaluridae family (lctalurus punctatus) have needs for 18: 2 ω 3 in the quantity of 1-2% or RUFA O. 5-1%. The fatty acids ω 6 row (18: 2 ω) 6 or 20: 4 ω 6) are important for the fish from Cichlidae family (Tilapia zillii and Orechromis nilaticus) in the quantity of 1%. Te sea fish Rhombus maximus and Pagnus major achieve the best growth when they receive HUFA ω 3 row up to 2% together with the food. Rancid ointment, eruk-acid from the rape oil, gosipol and cyclophrophenoid acid from the cotton seeds oil if added to fish food cause the reduced growth and pathologic changes on fish liver, kidneys, heart and gills

THE QUALITY OF WATER AND ICHTHIOFAUNA OF THE SOUTHERN LAKE IN OSIJEK – THE CONDITIONS FOR BIOMANIPULATION

Južno je jezero plitko (do 4 m dubine) umjetno jezero, površine 2,5 ha, a nalazi se unutar urbane cjeline grada Osijeka. Nakon dugogodišnjeg onečišćenja godine 1995. otpočela je njegova revitalizacija. Rezultati provedenih hidrobioloških istraživanja pokazuju osnovna ekološka obilježja Južnog jezera: veliku prozirnost vode, veliku količinu nutrijenata i bogato razvijenu makrofitsku vegetaciju. Analizom kvalitativnog sastava ihtiofaune utvrđeno je 13 vrsta riba iz 6 porodica, od kojih je vrstama najbrojnija porodica Cyprinidae. U kvantitativnom sastavu ihtiofaune brojnošću prevladava bezribica, a dobro su zastupljene sunčanica, babuška, crvenperka i bodorka. U trofičnoj je strukturi odnos grabežljivih vrsta prema mirnim vrstama nepovoljan. Radi daljnje revitalizacije Južnog jezera predlaže se primjena metode biomanipulacije: količinu makrofitske vegetacije smanjiti njezinim izravnim uklanjanjem i unosom biljoždernih vrsta riba, a nepovoljne trofične odnose unutar ihtiofaune mijenjati izlovom grabežljivih vrsta i unosom mirnih vrsta riba.The Southern lake is shallow (deep up to 4 meters) artificial lake with the ackerage of 6. 25. It is situated within the city of Osijek. Its reconstruction began in 1995, after it has been polluted for many years. The results of, hydrobiological examination show the basic ecological characteristics of the Southern lake: high transparency, great quantity of nutrients and highly developed macrophit vegetation. After the conducted analysis of the qualitative composition of the ichthiofauna, it has been found that the lake has 13 species of fish form six families, with the greatest number of them coming from Cyprinidae family. idae family. The fish species that outnumbers all other in the quantitative composition of the ichtiofauna is P. parua, but also well represented are L. gibosus, C. carrasius gibelio, Scardinius erythrophthalmus and Rutilus rutilus. In the trophic structure, the ratio of the predatory species is disadvantageous in relation to the unpredatory species. The application of the biomanipulation method has been suggested for the further reconstruction of the Southern lake: the quantity of the macrophit vegetation should be reduced by the way of its direct removal and the input of the herbivore fish species. The disadvantageous trophic ratio should be changed by overfishing of predatory species within the ichthiofauna and the input of unpredatory fish species

Epiphytic metazoans on emergent macrophytes in oxbow lakes of the Krapina River, Croatia: differences related to plant species and limnological conditions

This study investigated the structure of the epiphytic metazoans on emerged macrophytes in the littoral zone of two oxbow lakes with different trophic levels. Differences in the diversity and density of the epiphytic metazoans were analyzed in relation to plant architecture (simple or complex stems), food resources (algae and detritus) and water characteristics (transparency and derived trophic state index). Asignificant negative correlation was found between detritus on plants as food resource, and diversity and density of epiphytic metazoans, indicating grazing of microphagous species. Rotifers dominated in diversity and density in the epiphyton on all habitats. Total density of metazoans, rotifers and copepods in epiphyton were significantly higher on Mentha in mesotrophic lake than on Iris in a eutrophic lake.We presume that macrophyte belt width and trophic state governed biotic interactions and consequently epiphytic assemblages more strongly than macrophyte architecture. However, a Mentha habitat showed a slightly higher density and diversity of epiphytic metazoans in relation to Iris at the same site, but these differences were not significant